MPI troubleshooting help

On my boat when the lanyard is pulled or even loose I get no power to crank, nothing on the dash volt meter, and nothing at the coil to deliver a spark. I am getting plenty of crank, 12.5+ on the volt meter, and spark for 1-2 complete engine revolutions. Then something tells the ignition relay to trip, and no more spark.

Two deliveries are on their way to my house - a replacement ignition module - which is somewhat of a hail mary, but at 80 bucks figured it was worth a try. And a merc ten point plug so I can power the starter and ignition without depending on boat wiring and ignition switch. Actually I could jam a wire into the boat end of the 10 point plug to accomplish the same, but figured it would be cleaner- could even go boating if it comes down to it- with the homemade harness. If neither of these get it done, I'll need someone with actual skill and experience to fix it. So will have to decide if I want to put the 350 back in for June boating, or just trailer it somewhere and wait until they can fix it.

Man, those ECM's are pricey. I wish I would have kept mine when the original 454 bit it 12 years ago. I sold it on ebay, don't think I got more then 200 for it. These days they run at least 600, as much as 1,500. It's a delco part, would think an auto one would work, but I guess not?
 
Something sounds odd about your lanyard kill switch setup .

I've never heard of one that will not allow the engine to crank if the lanyard key is removed . I believe it should only open the ignition circuit on both Run and Start ign key switch positions ( or close that circuit to ground it out on older 2 cycle O/B's), not affect the starter circuit , so it should still crank but not fire .

But maybe yours is different by design?
 
mine's always been this way - when it's pulled, no power to anything on the dash, so motor can't crank.

Does anyone actually wear their lanyard? I know I'm supposed to, and I think 15+ years ago I used it maybe once or twice. But can't remember last time I clipped it on. Remember plenty of times the boat wouldn't start, or stopped dead while running because it came loose.

Fedex drove around all day yesterday with my ignition module in their truck, but never attempted to deliver. Maybe today.
 
Only time I wore the lanyard was when I was alone in the boat.
 
thanks everyone for your help, but I am about ready to throw in the towel on this motor and take it to a shop ( out of the boat), throw my small block back in, and perhaps swap them in a month or two depending if the 7.4 is usable. I took a chance on a running take out, have had some luck in the past with three others I purchased for various boats, but it's not looking great this time. I actually had it running for about 10 minutes this evening, it was idling ok, restarted a few times with no issues, thought my new ignition module did the trick. Then I tried again after about 30 minutes, now I can't get it to start. Different problem though, now I am getting plenty of spark without cutting out, but won't start up. Fuel pressure at the end of the rail is 40-45, but cylinders don't appear to be getting the fuel. hate computers. give me back a damn carb and some points!
 
Soooo close!
Have you tried starting with the throttle lever all the way to WOT in order to shut off the injectors, just in case there is a flooded condition? Possibly with a quick shot of gaseous starting fluid to minimize add'l cranking?

Rechecked the ECC/ECM on-engine fuse? Gas itself is good quality / fresh?

Personally , I would really hate to ever regress back to carb , points, condenser and ballast resistor.

Do you think there is any chance the seller could have swapped back out the ignition module and possibly computer after the test run, in order to save the good ones for his other motor or other use?
 
I don't think the seller swapped the ECM, but not 100% sure. When he ran it at the shop I remember being glad it was under 500 hours on the motor, and thought it was 477. And now it's showing 466. Perhaps I got the number wrong - I suppose more likely than him swapping ECM's. But that thought has entered my mind, as I did not take the motor the same day I saw it run. I trust the guy, but I'm a dumbass who trusts everyone.

Anyways, this morning I went over to the shop to return the scan unit he let me borrow/rent. He asked if I changed the coil yet. At nearly 200 for the mercruiser coil, that was a part I had not thrown at the problem yet. I was sure since there was enough current in the wire to fire the timing light that I had spark. Apparently big mistake on my part. He couldn't talk me into buying one, but he had a loaner coil in the back that he let me borrow. Brought it home, after trip to store for a 12 point 3/8" socket ( why mercruiser?), engine fires right up! I guess I'm going to go try it again every 30 minutes, and see what happens -- beer after every time it starts, shot if it doesn't?
 
Well I sure hope that really did fix it "reliably", but whether or not that is the case you must be feeling pretty happy by now.:D (7hrs x 2beers/shots per hour....)

Not sure how accurate this is for MPI high energy coils, but suggest you test both old and "new" coil primary and secondary circuit resistance to see how much the coils differ from each other.
http://www.boatered.com/forum/topic.asp?TOPIC_ID=51465
 
yes. it's going to take a lot of boating before I have any faith that this engine will get me home. Will have to keep that in mind when planning trips.

I had to hack up the old coil pretty good, because the new one I bought ( at napa) didn't come with the bracket. I'll probably regret asking this, but any downside to using a napa coil ( $27 ) as opposed to the seira ( $95) or merc ( as much as $200)? Please don't start with the 'its going to blow up and your insurance wont pay the claims'. I'm well aware that any spark producing ( dist, alt, starter, etc) or fuel venting ( carb) components must be true marine parst. But a coil? Thing is sealed tight and not shooting any flames. It might even be marine rated for all I know, I gave the napa guy a mercruiser part number, and he handed me a coil.

Anyways, motor is back in the boat resting on the mounts. Wish I had a chance to get it wired up and running in the boat, but I got a little greedy Sunday and tried to drop it in with the exhaust bolted up. That didn't go to well. I also got suckered in by a Harbor Freight hoist that could supposedly lift 1,362 pounds. It could not even budge 1,000. But job is now complete. thanks again everyone for your advice and offers.
 
Alk-
Still working reliably on the new coil, I hope?
 
The weather has been killing me. Got the motor back in last Sunday, but was travelling all week so couldn't get everything finished up. Got the engine aligned, drive on and almost everything else done on Saturday - then it poured all day Sunday. I probably should have launched it today, but ended up spending 4+ hours cleaning & waxing. I made a real mess yanking the motor in and out two times. But boat is all cleaned up, and motor still runs. Hopefully will be able to get in the water next Saturday.

too soon to start the list of thing I should have done while the motor was out? paint the bilge, paint the oil pan, replace the shift cable, remove the y-pipe and get rid of the corsa stuff. there's probably more!
 
Sounds good on the motor front. Don't worry about that other "shoulda-list" stuff. You can always do that next year, or....

Get back out on the water... and take a magic carpet ride !
 
The weather and our schedule finally allowed for a day of boating yesterday. Good news is that the new motor runs fine - after I put a new alternator on it two weeks back. Bad news is a few new potential problems; as always appreciate any expert advice.

First issue is that my steering seems loose. Not as in play in the steering, just that the drive is very easy to turn - so I pretty much have to keep my hand on the wheel all of the time. Noticed that when the boat is up on the trailer ( engine not running) I can push the drive from one side to the other, and see the steering wheel spin. I don't think this used to be the case. Did I break something doing the motor swap?

My oil pressure in this motor seems low, but 2004 was the last time I ran this boat with a working gauge - so not sure what is should be? At idle it's touching 40 psi, every now and then it gets as high as perhaps 50 - but when running on plane and coming off, I saw it dip to 20, and lower. Is that a problem?

Last issue is the outdrive ( bravo 3) oil. After a 30 or so minute run on plane, not WOT but over 3800 rpms, caught the smell of burning oil. Shut the motor off and opened the hatch - and the reservior bottle for drive oil was bubbling and a bit foamy , and smoke pouring off the port exhaust manifold - assume from drive oil overflow spilling onto the manifold. Once it settled the fluid in the bottle looked fine, I was expecting it to be mostly water. So not sure if I am leaking water into the drive, or just overheating the oil? I have a drive shower, which I think has worked well for the past 8 years, which is the age of this drive.

I was a little nervous when I pulled the transom drain plug at the end of the day, afraid of a puddle of oil or water - but after putting 4 or so hours on the motor, looks like no leaks into the bilge.
 
Alk- How hot are the tops of the risers to your hand at fully warmed cruise rpm?. I'm wondering if you have a RW flow problem that is not cooling the exhaust sufficiently and drive is getting too hot even with the help of the shower?

Could just a little of the drive fluid be overflowing onto the the drive steering linkage, -enough to lube that and cable end?

You could pull the engines OP sender and temporarily screw in an OP mechanical test gauge for somewhat of a reality check. It's a good idea but keep in mind just like dash gauges the test gauge can get "off" too. I've seen one professional grade gauge be off 10 psi and dash gauges more than that. The 20 psi dip on plane sounds bad if it is correct.
Do you have the correct dipstick for your marine application ( tilt vs. no tilt)? Could the crankcase be over filled just enough to aerate the oil at higher rpm at times? When you check the dipstick after a run like that does it still look like good oil ( no water milkshake or gas dilution in oil)?

A slight intermittant short to ground from chafed sender wire or failing sender or gaue can also cause substantial dip in displayed OP, so the mechanical test gauge can rule that out.

What crank oil weight are you running, how old is it , and what are the max. engine temps ?
 
fresh 25w-40 mercruiser oil. Filled to proper level last time I checked. I'll probably try a mechanical gauge.

I am getting good raw water flow, temp stays right below 170 when travelling at idle / no wake speed, and drops a few degrees when on plane - and that's with 84 degree raw water -- assuming my temp gauge is accurate. I gave up about ten years ago trying to get good water flow thru the drive, blocked that off with the merc plate and cut the hose as per the mercruiser instructions. Now I pull the water from a scoop on the transom. With the thru hull exhaust I can see a good stream of water out of both sides. That is the same time I fitted the drive with the shower. Kind of looks funny - a basic bowrider with a transom scoop and drive shower, like the high performance guys - but after battling temperature demons for years, haven't had an issue ever since I went to this setup. And when I had the motor out I saw why. The motor end on the drive water hose was pretty much sealed shut - not sure how that happened, but wouldn't have been able to squeeze much more than a trickle of water through.
 
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